fix(golang): permissive regex rule for validation purposes

[elsapet]

Description

Ideally the go_lang_permissive_regex_validation rule would only trigger when the permissive regular expression is being used for validation-specific purposes. Unlike some frameworks (Ruby-on-Rails, PHP Symfony), with golang, we cannot determine how a particular regular expression is being used. For this reason, the rule was triggering on the compilation of permissive regex, rather than its use. However, this meant that we were seeing some confusing false positives with this rule -- for example, with Replace (where there is no real security issue).

To address this, we modify the rule so that it triggers only when a permissive regular expression is used with Match methods, as this is more likely to be a validation case. We hope that this will reduce the rate of false positives while still proving useful in alerting users to actual security issues.

Checklist

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• My rule has adequate metadata to explain its use.